Scientists want clear weather at volcano

NEW Zealand scientists are hoping for improved weather as they try to track the likelihood of further eruptions from Mt Tongariro.

The mountain's Te Maari crater erupted for about five minutes on Wednesday afternoon, emitting a plume of ash and gas up to 4km into the air.

It followed a larger eruption in August, and warnings a few days ago of heightened activity at Mt Ruapehu.

GNS geologist Nico Fournier says the team wants to measure gases coming from the mountain, but cloudy weather on Friday could make that difficult.

"What we want to know is how much gas is coming out of the volcano and to do that we circle around the gas plume and we make some measurements from an aircraft equipped with some sensors," he told Radio New Zealand.

"We need the plume to go essentially out from the volcano so we can circle it and go under and above it. The other thing we need is a good view and ... today's not looking essentially promising."

Dr Fournier said the volcano had been remarkably quiet overnight, but that doesn't mean it's calming down.

"The volcano can pretty much erupt at any time. The last eruption was only a few days ago so it's still pretty unstable, and it can occur with little or no warning at all."

He said Mt Ruapehu had also been quiet but there was still a slightly elevated risk.